We’re excited that you are interested in Flannel. The Flannel Docker charm compliments the core-docker charm by providing a UDP private network for your containers to communicate cross host. This will be a cornerstone project in the evolving container provider story as it moves forward and provide a viable option for networking in public clouds.
To get started, check out the User Docs. If you're interested in Contributing or filing a bug we have instructions under the Developer Docs.
The Flannel-Docker charm is a subordinate unit that deploys *onto* the containers you relate to the
docker-host relationship. This will allow flannel to co-locate its binaries with the Docker service to enable cross-host networking via a TUN/TAP Device. Or more commonly known as TCP over UDP networking.
The Flannel service is originally developed by CoreOS. The Flannel-Docker charm encapsulates the knowledge of getting started with Flannel and brings it to fit inside the Juju Ecosystem of orchestrating Docker and its containers.
flannel (originally rudder) is an overlay network that gives a subnet to each machine for use with Kubernetes. In Kubernetes every machine in the cluster is assigned a full subnet. The machine A and B might have 10.0.1.0/24 and 10.0.2.0/24 respectively.